Rubber drive for printing hammers



March 4, 1952 c. e. DUDIS RUBBER DRIVE FOR PRINTING HAMMERS Filed Oct. 5, 1950 I INVENTOR CHARLES G. DUDIS f @Ma HIS ATTORNEYS Patented Mar. 4, 1952 RUBBER DRIVE FOR PRINTING HA IV IMERS Charles G. Dudis, Dayton, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Application October 5, 1950, Serial No. 188,51?

This invention relates to improvements in operating means for printing hammers for accounting machines.

The object of the invention is to provide a rub-- ber spring drivefor. a printing hammer.

A specific object of the invention'is to provide arubber connection between the drive means and the printing hammer fol-actuating the printing hammer in its printing operation.

Another object of the invention is to provide a single drive member having a plurality of rubber bushings secured thereto, and a printing hammer secured to each rubber bushing, whereby the printing hammers can all be cocked from a single po'wersource, together with means to select one or more of the hammers to be'cocked by said drive member,

With these and incidental objects infview, the invention includes certain novel features of construction and combinations of parts, a preferred form .or embodiment of which is hereinafter de-.

scribed with reference to the drawing which accompanies and forms a part of this specification.

In said drawing;

Fig. 1 is a side elevation of the hammer selectin and operating mechanism;

Fig. 2 is a graph charting the movements of a printing hammer when released for a printing operation;

Fig. 3 is a detailview of the printing hammer cocking mechanism;

Fig. 4 is a sectional detail view showing how thehammers are mounted on the drive member and illustrates the rubber spring bushing connections for three of a plurality of hammers; and

Fig. 5 shows a modified means for selecting printing hammers for operation.

General description The invention, described in general terms, com-, prises rubber spring bushings mounted between- Claims. (01. '101'93) the printing hammers and a single shaft, together;

with means for selecting hammers to be operated for printing. The rubber springs comprise bushings of rubber, which are used in place of wellknown steel springs for forcing the'printing hammer against type characters to provide the proper printing pressure.

One of the problems in the use of steel springs for forcing a hammer against the type characters for printing operations is to prevent rebound of the hammers after the impression is-made;'which rebound often causes shadow printing. 'Tests' have demonstrated that no such rebound occurs with the use of the novelrubber spring-disclosed.

herein. The use of'rubber springs results in a; better'pririting pressure, so that superior print-1 ing impressions are obtained, and also makes the printing of carbon copies feasible, a result heretofore not found satisfactory when steel springs were used. Such superior printing results from a: quick, sharp blow, thus deliveringthe maximum: amount of energy in the shortest time. 1

The novel construction also provides an improved "printing operation in that the alinement of the face of the printing hammer is better main tained, due to the fa'ct'that the driving forceior the hammer is located around the axis of movement of the hammer. In prior mechanisms, the driving force is applied at a point remote from. the axis of the hammer and offset from the center of the hammer platen face. J-For example, in the machine disclosed in the patent to Shipley No:

1,817,883, the hammers H13, 104, and '1have:

their platens offset from the supporting arms, and, in use, there is a tendency for'the hammer platen to strike the type carriers at an angle, which results in one end of the platen striking first and then rocking across the faceof the type carriers, with the result that the printing is not uniform across the complete line of printing, and, in addition, the ribbon wears faster at the point of first impact. This excessivewear of the ribbon not only shortens its life but also h'as'a tendency to deplete the ink supply at this point. All these factors result in defective printing. Applicants novel construction causes the face of the hammer to strike an even blow distributed-over the entire face of the typecarrier'line.

Detailed description I I A plurality of printing hammers l0 (Figs. 1 and 4) arev provided... the number of hammers varying according to the number of columns of, data to be printed. The hub of each hammer IDs comprises a sleeve I I, in. which a rubber bushing I2 is inserted, and an inner sleeve 13 is inserted issued. to Picaquerez, and 1,782,770,

merits of thehub'.

link IT.

The inner; sleeves I3are secured to .a common drive shaft 14. Also secured to the drive shaft I4 is anarmlS, connected to anarm lli'bya The arm Hi is pivoted on a shaft I8 and can be connected to a pair of cam follower arms l9, either by a hub or through the shaft l8. The cam follower arms |9 are provided with rollers 20, coacting with a pair of cam plates 2| in the usual manner, and the cam plates are secured to a main shaft 22.

The hammers l may be provided with a split hub 23 (Fig. 1) to provide for radial adjustment of the hammer I0 on the sleeve instead of forming the sleeve directly on the hammer, as shown in Fig. 4. A screw 24 provides a means for clamping the split hub 23 on the sleeve M. This radial adjustment is provided to vary the energy stored in the rubber bushing, so that the impact of the printing blow can be varied according to the printing to be effected, such as the number of carbon copies desired.

Each hammer H! is provided with a stud 25, which is engageable' with a latch pawl 26 when the latter is "selectively released in a manner presently described. Thellatches 26 are pivoted on a. shaft 21, and each latch 26 is flexibly connected. to an arm 26, secured on the shaft 21. A spring 29 is stretched between a stud 30 on each latch pawl 26 and a stud 3| on each arm 28. A separate: latch pawl 26, arm 28, and spring 29 is provided for each hammer |0, so that the hammers can be selectively operated.

The shaft 21 (Fig. 3) is operated during machine operations by a pair of cams secured to the main shaft 22. One end of a pitman 36 is slidably mounted on the shaft 22, between the cam plates 35, and the pitman 36 has thereon two oppositely facing roller 31 coacting with the cam plates 35. The left-hand end (Fig. 3) of the pitman 36 is pivoted to an arm 38 on the shaft 21. The pitman. is moved, first to the right (Fig. 3), and then back to the position shown, for each printing operation. As illustrated herein, the, cam plates 35are constructed to oscillate the pitman twice during 7 each machine operation. Movement of the pitman to the right rocks the shaft 21 counter-clockwise (Fi s. 1 and 3 which. through the arm 28 and the spring 29, tends to rock the latch pawl 26 counter-clockwise to position a shoulder 39 thereon into the path of the stud 25. This movement of the latch pawl 26 is normally prevented-by a latch pivoted on a shaft 46., The latch 45 is notched to engage a. stud 41 on the latch pawl26. The notch in the pawl 45 is held in engagement with the stud 41 by a stud 48, which is engaged by a finger 49 on the latch 45.. The stud 48 is. carried by an arm 50 secured to the. shaft 46. A spring 5| is connected to the stud48 and a stud 52 on the latch 45 for a flexible connection whereby the latch 45 is selectively withdrawn from engagement with the stud 41.

The pawl 45 is selectively withdrawn from engagement with thestud 41 under control of a notched disk 53 secured to a shaft 54. During a machine operation, the shaft 46 is rocked counter-clockwise (Fig. l) and carries the stud 48 therewith and, through the spring 5|, tends to rock the pawl 45 likewise. If a notch 55 is in the path of movement of a finger 56 on the pawl 45,."the pawl 45 m'ovesto withdraw the notch therein from engagement with the stud 41, thus freeing the latch pawl 26 to position the shoulder 39 thereon into the path of movement of the stud 25. If no notch 55 lies in the path of the finger 56, the notch in the pawl 45 is not withdrawn from the stud 41,and therefore the latch pawl 26 is held inthe-iposition illustrated in- Fig. 1.

No means is disclosed herein for settin the disks 53 or for rocking the shaft 46, since this mechanism is well known in machines pf the type to which the present invention is shown applied. For a detailed description of these mechanisms, reference may be hadito United StatesiPatent No. 2,373,510, issued to Spurlino etal. on April 10, 1945.

The disks 53, one for each hammer H), are selectively positioned by a differential mechanism controlled by manipulative devices, in the manner disclosed in said patent, for selectively determining which hammer I0 is to operate in a given machine operation for the purposes described in said patent. It is sufficient to say that, when a notch 55 is positioned in the path of the finger 56, the hammer will operate toeifect a prinfting record, and, when no notch 55 is in the path of the finger 56, no printing will be performed.

" Operation (Assuming that a printed impression is to be made during an ensuing machine operation, during the initial part of the machine operation the selecting disk 53 is selectively adjusted to position a notch 55 into the path of the finger 56, and thereafter the shaft 46 is rocked counter-' clockwise (Fig. 1). Since a notch 55 i in the path of the finger 56, the arm 50 on the shaft 46, through the spring 5|, rocks the pawl 45 to disengage it from the stud 41 on the latch pawl 26. Immediately thereafter, the cams 35, acting through the pitman 36 and the arm 38, rock the shaft 21 to move the stud 3| on the arm 28 upwardly, thus permitting the spring 29 to rock the latch pawl 26 into the path of movement of the stud 25 on the hammer l6. After the latch pawl has assumed such moved position, the cam hammer lll'likewise, until the hammer I0 is arrested when the stud 25 thereon contacts the shoulder 39 on the latch pawl 26, whereupon the hammer is stopped,.but the shaft |4 continues to rotate. This continued rotation of the shaft |4 produces a torsional shear of the rubberbushing I2 and produces potential energy therein.

. After the proper torque has been produced in the rubber bushing l2, the latch pawl 26 is withdrawn by the cam plates 35 to release the hammer I0 to strike a printing blow on the type carriers 66, carried on a stationary rod 6|. At. the same time, the shaft l4 begins to reverse its movement, thus starting to return the hammer toward its normal position. The effect of this action i described below. u h

The characteristics of the rubber used for a given printing mechanism will vary with its design, its weight, and the force required to obtain a clear printed impression, and the proper size and characteristics of the rubber bushing must be determined by experiment.

A plurality of printing impressions can be made during each machine operation, the number being controlled by the shapes of the cams 2| and 25.

.As illustrated herein, these cams are shaped to "cause two impressions to be taken by each cocked and released printing hammer during every machine operation.

In the application illustrated, rubber of 60 I recorder was used to obtain curves indicating.

movements of the hammer when printing. The paper speed on the drum was set to a speed of inch per milli-second. The curves obt ined are illustrated in Fig. 2. In Fig. 2 line A indicates the normal position of the hammer. Line B indicates the rise of the hammer when the stud 25 contacts the shoulder 39 of the latch pawl 26, and the length of line B represents the time during which the hammer is held by the latch pawl 26 and the rubber bushing vl2 is being twisted by the shaft M, to store energy therein. At .the point C, the 1atch pawl 26 is pulled ofi the stud 25; and the hammer I is snapped upwardly to strike the type character wheel. 60 at point D, and the high point is illustrated by chain line D. At this time, the shaft 14 starts to return and tends to pull the hammer down. This movement causes a drop E in the curve, which indicates a rapid fall of the hammer to the point F. A series 0:! rebounds occur, which are indicated at G, H, and I, which rebounds are very small and do not reach the height D, which is necessary to make a secondprinted impression. This is due in part to the return movement of the shaft 14 and the tendency to restore the hammer to normal position immediately the latch pawl 26 is withdrawn, and in part to the return of the rubber bushing to its state of rest. This results in a novel m thod of preventing a second impression due to rebou d, and therefore a rubber-spring-operated hammer does not require additional rebound-preventing mechanisms, while at the same time the energy stored in the rubber spring l2 by the t isting action is sufficient toobtain a clear print on a plurality of carbon copies, when such copies are 7 desired: This superior printing result is rbtained due to the rapid action of the rubber spring when released, which gives a strong impression blow. 1

The operation of the hammer in when it is ot arrested by the latch pawl 26 is indicated on the graph (Fig. 2) by the dotted line J. This condition prevails when no notch 5'5 is opposite the finger 5B, and the latch 45 holds the latch pawl 26 in. normal position. When the sha t I4 is rocked, the hammer l0 rises to the level of the chain line K, which is below the printing roint '3, and therefore no impression is made. The ighest positionassumed by the ham er in this operation is shown by chain line in Fig. 1.

Fig. 2 illustrates the vibrations of the hammer when operated by the mechanism as illustrated; that is, when the cam plates 2| are d signed to restore the shaft [4 immediatelv the printing impact takes place. If insome installations it is necessary to delay the return of the hammer until the latter stage of the machine oper tion, the vibrations of-the hammer have been shown by experiment to be substantially like those illuse trated by points H and I along the line K. In no case does the hammer rise sufficiently to cause shadow printing by a second impact on the type carrier by rising to the height of point D.

V In addition to the improved printing results described, the present invention also adapts itself to a simpler hammer-selecting means for columnar printing. Any number of hammers I0 can be arranged on the common shaft I 4, nd only one operating mechanism need be furnished for actuating all the hammers singly, or in any combinationyor all at one time; The selection of hammers is determined'bv the differential positioning of the selecting disks 53, one being provided for each latch 45, and one latch 45 is provided for each latch pawl 26.

By referring to Fig. 4, it will be apparent that selectively, either.

all the rubber bushings l2 will be actuated through the one arm l5. Whether or not the bushing will be twisted depends on the position of the corresponding latch pawl 26. In this way, any one or more hammers can be actuated to print. in its corresponding column on the record material.

Modified form Fig. 5 discloses a modified form of hammer lug 12 is secured to'the plate 68, and the lug is tapped to receive an adjusting screw 66. By means of the screws H and 66, the shoulder 61 can be adjusted on the periphery of the hammer hub to vary the torque when the machine is oper-' ated. A selecting pawl 69 is rotatably mounted on the shaft 46, which is provided with a finger 49 in the same manner as the latch pawl 45. The finger 49 is held in engagement with the stud 48 on the arm 50 by the spring 5|, one end being attached to a stud 52 on the selecting pawl '69 and the other end being attached to the aforesaid stud 48. The pawl 69 is provided with an upright finger 10 movable into, or out of, the path of the shoulder 67. i The position assumed by the finger i0 is controlled by the notched disk 53 in the same manner as in the first form described above. To this end, the notched disk is provided with one or more notches 55, and the selecting pawl 59 is provided with a finger 55.

In its operation, when the finger 56 on the S87 lectingpawl 69 enters anotch 55, the finger 10 moves into the path of the shoulder 61, and there; after, when the shaft [4 is rocked, the shoulder 61 engages the end of the finger T0, whereupon the hammer is arrested and the rubber bushing l 2 is twisted, in the manner described above,- to store energy therein to print when the hammer is released. In this form of embodiment of the invention, the hammer B5 is released for its print-'- ing stroke when the shaft 46 is rocked to withdraw the finger 56 from the notch 55, whereupon the upright finger will also .be withdrawn from engagement with the shoulder 61. The amount of energy stored is determined, in part, by the distance the stop 6'! is adjusted from the top of finger 1B. The mechanism for rocking the shaft 46 is shown and described in the above-mentioned Spurlino et al. patent. 1

While the forms of the invention shown and described herein are admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the forms or embodiments disclosed herein, for it is susceptible of embodimentin various other forms. 1

What is claimed is: I

1. In a printing mechanism of the class described, the combination of a printing hammer having a hub; a drive shaft; a rubber spring to actuate the hammer, said rubber spring compris ing a bushing bonded to the inner wall of the hub of the printing hammer and to the outer wall of the drive shaft a latch pawl movable to en: gage the printing hammer to holdfthe printing hammer as the drive shaft is operated to t rsionf ally shear-the rubber bushing to create torsional energy in the rubber bushing; means to there; after withdraw the latch pawl from engagement with'the hammer to release the said torsional 'energy'and. thereby operate the hammer for makhaving a hub; a drive shaft; a rubber spring to actuate the hammer, said rubber spring comprising a bushing bonded to the inner wall of the hub of the printing hammer and to the outer wall of the drive shaft whereby the printing hammer can be operated by the drive shaft; a latch pawl movable to engage the printing hammer to hold the printing hammer against movement when the drive shaft is operated; a latch normally engaging and holding the latch pawl in a position where the latch pawl cannot engage the printing hammer; means to selectively control the release of the pawl from the latchpawl to cause the latch pawl to move into engagement with the printing hammer whereby the hammer is selectively held as the drive shaft is operated to torsionally shear the rubber bushing to create potential energy in the rubber bushing; means to withdraw the latch pawl from engagement with the printing hammer after the torsional energy has been created to thereby cause the rubber bushing to operate the hammer for making a printing stroke; and means to operate the drive shaft.

3. In a printing mechanism of" the class described, the combination Of a printing hammer having a hub; a drive shaft; a rubber spring to actuate the hammer, said rubber spring comprising abushing bonded to the inner wall of the hubof the printing hammer and to the outer wall of the drive shaft; a latch pawl movable to engage the printing hammer to hold the printing hammer as the drive shaft is operated to torsionally shear the rubber bushing to create potential energy in the rubber bushing; means to thereafter withdraw the latch pawl from engagement with the hammer to release the said energy and thereby operate the hammer for making a printing stroke; and means to operate the drive shaft to first torsionally shear the rubber bushing and to return the drive shaft and the bushing immediately the hammer makes its printing stroke to prevent the hammer from rebounding sufiiciently to cause a second printing stroke.

4. In a printing mechanism of the class described, the combination of a printing hammer having a hub; a drive shaft; a rubber spring to actuate the hammer. said rubber spring comprising a bushing bonded to the inner wall of the hub of the printing hammer and to the outer wall of the drive shaft whereby the printing hammer can be operated by the drive shaft; a latch pawl movable to engage the printing hammer. to hold the printing hammer against movement when the drive shaft is operated; a latch normally engaging and holding the latch pawl in a position where the latch pawl cannot engage the printing hammer; means to selectively control the release of the pawl from the latch pawl to cause the latch pawl to move into engagement with the printing hammer whereby the hammer is selectively held as the drive shaft is operated to torsionally shear the rubber bushing to create potential energy in the rubber bushing; means to withdraw the latch pawl from engagement with the printing hammer after said energy has been created to thereby cause the rubber bushing to operate the hammer for making a printing stroke; and means to operate the drive shaft to first torsionally shear the rubber bushing and to return; the drive shaft and the bushing immediately the hammer makes its printing stroke to prevent the hammer from rebounding sufiiciently to cause a second-printing stroke.

5. In a printing mechanism of the class described, the combination of a printing hammer having a hub; a drive shaft; a rubber spring to actuate the hammer. said rubber spring comprising a bushing bonded to the inner wall of the hub of the printing hammer and to the outer wall of the drive shaft whereby the printing hammer can be operated by the drive shaft; a latch. pawl movable to engage the printing hammer to hold the printing hammer against movement when the drive shaft is operated; a latch normally engaging and holding the latch pawl in a position where the latch pawl cannot engage the printing hammer; means comprising a differentially settable' notched control disk coacting with the pawl to selectively control the release of the pawl from the latch pawl to cause the latch V pawl to move into engagement with theprinting hammer whereby the hammer is selectively held as the drive shaft is operated to torsionally shear the rubber bushing to create potential energy in the rubber bushing; means to withdraw the latch pawl from'engagement with the printing. hammer after the said energy has been created to thereby cause the rubber bushing to operate the hammer for making a printing stroke; and means to operate the drive shaft.

' 6. In a. printing mechanism of the class described, the combination of a printing hammer having a hub; a drive shaft: '2. rubber spring to actuate the hammer, said rubber spring comprisinga bushing bonded to the inner wall of the hub of the printing hammer and to the outer wall of the drive shaft whereby the printing hammer can be operated by the drive shaft; a springurged latch pawl movable to engage and hold the printing hammer against movement when the drive shaft is operated; a spring-urged latch normally engaging and holding the latch pawl in a position where the latch pawl cannot engage the printing hammer; a differentially settable notched control plate; means on the latch engageable with the notched control plate to selectively control the movements of the latch whereby the latch may be disengaged from the latch pawl to release the latch pawl for movement'into engagement with the hammer, whereby the hammer is held when the drive shaft is operated to twist the rubber bushing and thereby create potential energy in the rubber bushing; means operable to engage the latch pawl with the hammer before the said energy is created and towithdraw the latch pawl from engagement with the hammer after said energy has been created to thereby cause the hammer to make a printing stroke; and means to operate the drive shaft.

'7. In a printing mechanism of the class described, the combination of a printing hammer, operating means for the printing hammer consisting of a rubber bushing connected to the printing hammer and to a drive shaft therefor, a means to selectively arrest movement of the hammer, means to rock the drive shaft to create potential energy in the rubber bushing when the hammer is held, and means to withdraw the arresting means after said energy has been created to cause the force to operate the printing hammer.

8. In a printing mechanism of the class described. the combination of a pivoted printing hammer, operating means for the printing hammer comprising a rubber bushing connected to the hammer around the axis of its pivotal movement, a drive means also connected to the rubber bushing, means to selectively arrest the printing movement of the hammer, actuating means to actuate the drive means while the hammer is arrested to store energy in the bushing, and. means to withdraw the arresting means after said energy has been stored in the bushing to cause the hammer to make a printing stroke.

9. In a printing mechanism of the class described, the combination of a printing hammer, operating means for the printing hammer consisting of a rubber bushing connected to the printing hammer and to a drive shaft therefor, a means to selectively arrest movement of the hammer, means to rock the drive shaft in one direction to create potential energy in the rubber bushing when the hammer is held, and means to withdraw the arresting means after the said energy has been created to cause the energy to operate the printing hammer, said means to rock 10 the drive shaft movable in a reverse direction immediately the hammer is operated.

10. In a printing mechanism of the class described, the combination of a pivoted printing hammer, operating means for the printing hammer comprising a rubber bushing connected to the hammer around the axis of its pivotal movement, a drive means also connected to the rubber bushing, means to selectively arrest the printing movement of the hammer, actuating means to actuate the drive means in one direction while the hammer is arrested to store energy in the bushing, and means to withdraw the arresting means after said energy has been stored in the bushing to cause the hammer to make a printing stroke, said means to actuate the drive means movable in a reverse direction immediately the hammer starts its printing stroke.

CHARLES G. DUDIS.

No references cited. 

